One of the central topics of this Program Project (PO1) is that acute lung injury is associated with increased production of reactive oxygen species that may be responsible, at least in part, for oxidative injury to pulmonary cells. This suggests that monitoring free radicals, biomarkers of oxidative stress and antioxidant status is essential for understanding the mechanisms of acute lung injury and developing novel optimized therapeutic strategies. The assays of oxidative stress will be performed in the core on Biomarkers of Oxidative Stress (COBOS). The core has been designed to allow researchers in the projects to measure biomarkers of oxidative stress using sophisticated state-of-the art techniques to assess several of the different relevant parameters. Specific Aims of the core are: 1. Provide professional expertise in the design and implementation of experiments using adequate techniques for assessment of biomarkers of oxidative stress and antioxidants. 2. Prepare, store and optimally analyze samples of tissues, cells and biological fluids to detect free radical intermediates, as well as biomarkers of oxidative stress in major classes of biomolecules (proteins, DNA, and lipids). 3. Evaluate experimental results and propose subsequent experimental direction. 4. Provide training in the use of and access to any instrumentation and techniques used with the program project to assess biomarkers of oxidative stress and antioxidant status. Overall, COBOS will be central to the planning and execution of experiments on oxidative stress md antioxidants within the program.